Haram Lee

Despite advances in the preparation of metal oxide (MO) nanoparticles (NPs) as catalysts for various applications, concerns about the biosafety of these particles remain. In this study, we prepared transition metal-doped cerium oxide (TM@CeO2; TM = Cr, Mn, Fe, Co, or Ni) nanoparticles and investigated the mechanism underlying dopant-dependent toxicity in HaCaT human keratinocytes. We show that doping with Cr or Co but not Fe, Mn, or Ni increased the toxicity of CeO2 NPs in dose- and time-depende

Abstract Perovskite solar cells are easily decomposed by ultraviolet rays. In order to limit the function of TiO 2 as a photocatalyst, ZnGa 2 O 4 nanoparticles were mixed into a mesoporous TiO 2 layer. The bandgap of the mixed layer increased by 0.1 eV and the efficiency of perovskite solar cell increased by 0.5%. However, it acts as a resistive element and lowers the current. Since ZnGa 2 O 4 emits absorbed ultraviolet rays in blue, a thin film is additionally formed on the glass substrate to c

Abstract We achieved the heteroepitaxial growth of Sn-incorporated Ga 2 O 3 (Ga 2 O 3 :Sn) thin films on sapphire (0001) substrates using radio-frequency powder-sputtering. Synchrotron X-ray diffraction at out-of-plane and in-plane Bragg peaks revealed that the Ga 2 O 3 :Sn thin films were composed of corundum α and monoclinic β phases, both being epitaxial to the sapphire (0001) substrates. Epitaxial relationship can be summarized as β –Ga 2 O 3 [−201]// α –Ga 2 O 3 [0001]//sapphire[0001] in th

Abstract The ZnGa 2 O 4 down-converting layer was deposited on the incident side of perovskite solar cell. The down-converting layer was coated by sol-gel spinning. Perovskite solar cells with ZnGa 2 O 4 films operate without loss of efficiency and produce additional current when irradiated with 254 nm light. It was confirmed that nano devices with both a function as a UV-C sensor and a function as a solar cell can be implemented.

Abstract In this study, we focused on the changes on the perovskite layer by annealing. A two-step annealing process, which changes the temperature and time in the annealing process of the perovskite film, is important to obtain a more efficient solar cell. The perovskite synthesis proceeds rapidly, but a significant amount of lead iodide residue remains. Additional annealing is needed to reduce the lead iodide residue that causes degradation in efficiency. A solar cell with an average efficienc

A ZnGa 2 O 4 :Eu 3+ layer was deposited on the incident surface of a perovskite solar cell (PSC) to convert ultraviolet rays into current within the solar cell. The ZnGa 2 O 4 :Eu 3+ layer was deposited using the sol–gel method, and the thickness of the film was controlled using the number of spin coatings. When the coating was applied six times, a layer with almost no oscillation due to reflection was fabricated. It was confirmed that the efficiency of the PSC was not adversely affected by the

In this study, the general sound environment characteristics of open-plan office (OPO) were investigated, and just noticeable difference (JND) of sound pressure level of speech at a distance of 4 m (Lp,A,S,4m) suggested in ISO 3382-3 was suggested. First, in order to understand the sound environment characteristics of OPO, one minute sound sources recorded in 8 offices were collected and physical and psychological acoustic characteristics were analyzed. A total of 30 office workers were subject

This article examines William Blake’s critique of instrumental reason in The Four Zoas to rethink the politics of his later poetry. Rather than signaling his quietism, Blake’s poem registers his insights into emerging political strategies that produce governable bodies by encouraging rational self-mastery and the pursuit of self-interest. I argue that Blake represents proto-biopolitical thinking as such in criticizing Malthus’s political economy and radical political discourse of the 1790s.

This article examines William Wordsworth’s political sonnets in his 1807 volume of poetry to reconsider their political implications in post-revolutionary Britain. While critics have viewed these sonnets as evidence of the poet’s embrace of patriotism and conversion to conservative ideology, I argue that his sonnets are far too ironical and (self-)critical to be characterized as jingoistic. In these poems, Wordsworth does not so much endorse patriotism as he critically reflects on its conceptual

With the rapid expansion of AI agent services, this study examines how service changes in SK Telecom's “Adot Phone” affect user perception. To investigate this, we analyzed Google Play Store review data using a combination of NLP techniques, including KoBERT-based sentiment analysis, Latent Dirichlet Allocation (LDA) topic modeling, and Interrupted Time Series Analysis to assess the impact of the service change. The results show that the service modification led to a notable drop in positive sen

The emotional restorativeness of soundscapes, akin to the healing effects of natural green spaces, can induce recovery from life-cycle emotional and cognitive-related disorders. A digital therapy program that supplements medication was developed through soundscape experiences in a multi-user VR environment and evaluated psychophysiologically. Initially, the program provided natural environment-based role-playing for the treatment of children with ADHD and utilized soundscape audio-visual content

This article offers a critical examination of Max Frisch’s Man in the Holocene (1979) as an Anthropocene novel. I argue that Frisch’s novel represents the Anthropocene by engaging with its conceptual problematics concerning temporality and agency. Recent ecocritics have viewed the novel as challenging anthropocentric thinking by foregrounding geological time, the enormous scale of which relativizes and marginalizes the place of humanity in the world. In my view, however, Frisch confronts not onl